Hesitation, stalling Please Help!!!

I have a 91 s10 blazer with a 4.3 V6. about two weeks ago coming home from work it started hesitating (bucking) realy bad so I pulled into a rest area were it stalled. It will start back up but you can smell fuel as if it was fluded.
After two weeks I have noticed this pattern: in the morning starts up just fine after about 10 min of driving it starts its hesitating. If I have to come to a stop when Its doing this it will stall. If I can keep accelerating through it it will eventualy stop ( warm Up? ) and run fine the rest of the way to work.

I have changed the plugs, coil, cap, cleaned the TBI with throtle body cleaner.
This is driving me crazy.
Somone please help!!!!

Get the computer read first, but I'd almost think Oxygen sensor.

I would say, check for codes .
When was the last time the fuel filter was changed?
There's a common problem with bad grounds /connections on fuel pump.(you have to change it to correct it.)
Just a few other things to consider...

check your egr valve. does your check engine light come on?? if not you wont have any codes stored.
if so to read the code is easy. all you need is a wire about 3 or 4 inches long. for a 91 you dont need a code reader the truck will give you the codes its self with a very simple procedure. let me now about the engine light and if you need to know how ill post a nother reply to let you know how.
i have a 91 s10 blazer myself . similar problem turned out to be carbon build up in the egr valve
keeping it open. easy to take off and clean.
let us know how you are doing.

I would say, check for codes .
When was the last time the fuel filter was changed?
There's a common problem with bad grounds /connections on fuel pump.(you have to change it to correct it.)
Just a few other things to consider...


The thing is it happens with an almost exact pattern every time I leave the house it does this about 10 min. into my ride and continues for about 3 or 4 miles. As if its somthing to do with warming up? This is why I can't see it being a bad ground or connection ( of course I could be wrong ). Also the check engine light is not on.

I thank you all for the replys. Please keep the ideas coming.

The thing is it happens with an almost exact pattern every time I leave the house it does this about 10 min. into my ride and continues for about 3 or 4 miles. As if its somthing to do with warming up? This is why I can't see it being a bad ground or connection ( of course I could be wrong ). Also the check engine light is not on.

I thank you all for the replys. Please keep the ideas coming.

Get the codes scanned!

"OBD I will not have a code unless the SES light is on" -GM Head Tech.
As for what you should do, I am sorry to say it is anyone's guess.

"OBD I will not have a code unless the SES light is on" -GM Head Tech.
As for what you should do, I am sorry to say it is anyone's guess.

Bullshit, it will store the codes unless the computer is reset.

That is correct, it will store codes untill reset or the truck is started a certain number of times. From what he said unless a trouble code is triped, causing a dash warning light to come on, nothing is stored in OBD I computer systems. Is this correct, I dont know, just what the GM master Tech told me.

That is correct, it will store codes untill reset or the truck is started a certain number of times. From what he said unless a trouble code is triped, causing a dash warning light to come on, nothing is stored in OBD I computer systems. Is this correct, I dont know, just what the GM master Tech told me.

Not much of a master tech.

It is common knowledge that it will record and store any code unless it is the real primitive OBDI from the mid late 80s.

this is from the haynes manual: the computer command control(ccc) has a built-in dianostic feacture which indicates a ptoblem by using a check engine soonlight
on the instrument panel. when the light comes on during normal vehicle operation, a fault in one of the informationsensor circuits or the emc itself has been detected. more importantly, the source of the problem is stored in the ecm memory.
soooo, if light has never been on no code exept for 12 letting you know the system is working(self dianostic).

Yip, and if there was EVER a code, it would be stored.

he said his light was not on

he said his light was not on

And that means there is no codes stored?

he said he changed the coil so i assummed he discconnnected his BATTERY when he did. which would have erased any prior codes.

Let's not assume anything until the thread starter responds.

I did disconect the battery when I installed the coil last friday. The only code present is a code 42 (EST) which is from this past weekend when I set the timing.

This problem is making me crazy!!

Clean and reinstall the IAC.

I don't think you understood me. Lets say the O2 sensor gives a strange reading to the computer, this is read by the OBD I computer. It then both stores the code for O2 sensor and turns on the SES light. What I am trying to say is if the SES light did not come on and has not within a number of starts (this is a lot of starts mind you) or sense the battery has been disconnected there will be no codes stored in the computer. Even ignoring the GM Master Tech, why would the computer trip a trouble code and not turn on the SES, oil, or other idiot light?

Bot all codes throw the check engine light on.

Ok I removed the IAC valve. It's was pretty gumed up. My question is shouldn't the pintle be able to move in and out? This thing does not move at all even after my best atempts at cleening it. Is it time for a new one?

Thanks

Ok I removed the IAC valve. It's was pretty gumed up. My question is shouldn't the pintle be able to move in and out? This thing does not move at all even after my best atempts at cleening it. Is it time for a new one?

Thanks

No, it should not move. It should be 28mm (1.10inches) from the tip to the flange.

Clean the valve with a toothbrush and some throttle body or carb cleaner and make sure all the carbon and gunk is removed and the valve is clean.

Also spray some cleaner into the hole in the engine where you insert it and clean the passages too. They often get clogged with grime. Get in there and dissolve all that crap out and make sure it is clean.

Also, best that you tighten all the hose clamps on your air filter assembly seeing that is where most of the grime is coming from.

Then reinstall the valve, make sure you don't ruin the O-ring, reset you computer by pulling the negative battery cable for 5 minutes. Then start the engine.

It will run a little rough for a bit as it clears the cleaner and relearns the idle. After 5 minutes or so of idling, put your foot on the brake and hold it there and put the tranny in drive and hold still for 3 minutes so the engine can relarn the idle while in gear.

You should be good to go from there.

Vtmech Is Right After So Many Crnaks It Will Clear Out! If Read Gm Tech Manual It Will Tell You

I replaced the IAC valve and all is well :-) Thanks BlazerLT
you da man! I love this forum. I have to wonder how much money it would of cost me to take it into a shop ($200- $300)? The IAC valve was $30.00 at advanced auto parts. Thanks to all that replyed.

I replaced the IAC valve and all is well :-) Thanks BlazerLT
you da man! I love this forum. I have to wonder how much money it would of cost me to take it into a shop ($200- $300)? The IAC valve was $30.00 at advanced auto parts. Thanks to all that replyed.

Glad to have helped you. :D

Ha Ha!! You guys were wrong!

Ha Ha!! You guys were wrong!

This is not me, administrators are tracking this guy right now and his IP address is logged and currently being traced.

This is not me, administrators are tracking this guy right now and his IP address is logged and currently being traced.

Nothing is safe these days.

I see that he doesn't have your Blazer picture, so I believe you... Although I sure thought that you became conceded for a while...sorry